Invasive Species Management

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Need Noxious Weed Advice?

We are able to answer calls and questions. Our hours are Mon -Thur 6:30 am - 5 pm.  See our contact information on the right-hand side of this page.

What We Do

Orange hawkweed flowerhead.The Jefferson County Invasive Species Management program provides the public with information and offers solutions for managing invasive species and supports good stewardship of the land.  

We ensure the compliance with Colorado’s noxious weed, forest pest, and agricultural vertebrate pest regulations on private, county, and state lands.  We also provide technical assistance and support to county departments who are responsible for managing county owned lands.

The program coordinates with private, local, state, and federal agencies to achieve regional pest control.

Who We Are

Canada thistle flower.Our staff includes the Invasive Species Management Coordinator and limited summer help.

Weed of the Month

Each month we will feature a noxious weed to help landowners identify weeds they may encounter on their property.

Perennial pepperweed

September 2022

Perennial pepperweed 

Lepidium latifolium

Perennial pepperweed is a member of the mustard family (Brassicaceae).  Populations form dense monocultures that are easily spread by root fragments and seed.  This plant can establish in a wide range of environments to including flood plains, pastures, roadsides, and residential sites.

Plants grow up to 6 feet tall.  Leaves are bright to gray-green with toothed to entire edges and have a prominent white mid-vein.  Basal leaves are larger than upper leaves.  

Multiple stems grow from the crown. Older stems are woody and can persist, forming a thicket that inhibits other plants from growing.

It has small white flowers that form in dense clusters near the end of the branches.  Two seeds form in rounded, flattened and slightly hairy reddish-brown fruits.

Perennial pepperweed probably entered the US prior to 1940 in a shipment of beet seed (Beta vulgaris) from Europe.

It prefers to grow in moist areas but can adapt where conditions are drier.  Perennial pepperweed is saline tolerant. It is also a salt pump, that is the rhizomes absorb salt from the soil, accumulate it into its leaves, and upon senescence its salty leaves fall to the soil. Salinity does not appear to affect seed germination.  This plant is known to thrive where Salt cedar (Tamarisk spp) populations exist.  

Herbicide treatment is best at the early bud stage or in the fall. Removal or cultivation is not very effective in large established sites because the root system extends deeply in the soil and fragments will give rise to new plants. 

Resources

UC IPM How to Manage Pests 

USDA Field Guide for Managing Perennial Pepperweed in the Southwest 

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A Landowner's Guide - Developing a Noxious Weed Management Plan

We developed this guide to assist landowners.  The information provides steps to develop a management plan for properties that have noxious weeds.

Download your copy

yellow_flag_iris Weed Spotter

The Weed Spotter program is a citizen science based effort to detect 6 high priority species on Jeffco Open Space parks.  Learn more at our Citizen Science page.